[Despite] our always contributing to the reality we experience, there is something apart from ourselves to which we can be true — that reality, in other words, is not purely made up by the brain. There is a relationship there — something to be true to. Assuming there is something there to know implies that some understandings will inevitably be better than others. And since each hemisphere provides a different understanding of it, it is perfectly coherent — and indeed necessary — to ask which is superior. (The validity of the question is not affected by the observation that we can, and may be best to, use both.) If a pilot is flying blind and has two navigation systems to rely on, each of which, though they differ, provides significant information, the criterion for having to prefer one over the other is clear: following which one is less likely to lead to a crash. Or again, as a piece of music cannot be experienced without a player, who inflects what it is that we hear, there is nonetheless such a thing as a better or worse performance, one that is more or less faithful to the potential enshrined in the piece — a potential that is, essentially, the piece of music, and becomes realised in every true performance, The arbiter, then, in either case, is the experience of the whole embodied person as he or she responds to a more, or less, accurate — a richer, or poorer — account of the world.

— Iain McGilchrist, The Matter With Things: Our Brains, Our Delusions, and the Unmaking of the World, 1:379–80.